Propeller shaft and constant velocity universal joint for a propeller shaft

Abstract

The width (L) in the circumferential direction of the outer surface 2 a of an inner joint member 2 is L≧3.5 mm. When the assembly angle (θ 0 ) of the torque transmitting ball 3 is set to 50°, the width (W) in the axial direction is set so that the ratio Rw (=W/PCD SERR ) between the width (W) in the axial direction and the pitch circle diameter (PCD SERR ) of the teeth of an engagement portion 2 c lies within the range of 0.57<Rw≦0.95. Thus, while enabling the assembly of the torque transmitting ball at the assembly angle θ 0 =50°, cold forging on the inner joint member 2 is made possible, thereby reducing the processing cost. By reducing the width (W) in the axial direction as much as possible, the weight, dimension, and material cost can be reduced.

What is claimed is:  
     
       1. A constant velocity universal joint for a propeller shaft having a shaft portion, comprising: an outer joint member in which eight guide grooves extending in an axial direction are formed on an inner spherical surface thereof; an inner joint member in which eight guide grooves extending in the axial direction are formed on an outer spherical surface thereof and an engagement portion having teeth which come into tooth-engagement with the shaft portion of the propeller shaft is formed on an inner surface thereof; eight torque transmitting balls disposed in eight ball tracks, respectively, each ball track formed by cooperation between one of the guide grooves in the outer joint member and a corresponding one of the guide grooves in the inner joint member; and a cage for holding each one of the torque transmitting balls, 
       wherein the ball tracks widened toward one side in the axial direction forming wedge shape configurations, and  
       a ratio Rw (=W/PCD SERR ) between an axial width (W) in the axial direction of the inner joint member and a pitch circle diameter (PCD SERR ) of the teeth of the engagement portion is 0.57<Rw≦0.95 and a circumferential width (L) in the circumferential direction of the outer surface between the guide grooves of the inner joint member is L≦3.5 mm.  
     
     
       2. A constant velocity universal joint for a propeller shaft according to claim  1 , wherein the inner joint member is formed by cold forging. 
     
     
       3. A constant velocity universal joint for a propeller shaft according to claim  1 , wherein a ratio r 1  (=PCD BALL /D BALL ) between the pitch circle diameter (PCD BALL ) of the torque transmitting balls and the diameter (D BALL ) of each torque transmitting ball is 3.3≦r 1 ≦5.0 and a ratio r 2  between the outer diameter (D OUTER ) of the outer joint member and the pitch circle diameter (PCD SERR ) of the teeth of the engagement portion is 2.5≦r 2 ≦3.2. 
     
     
       4. A constant velocity universal joint for a propeller shaft according to claim  1 , wherein the outer joint member is coupled to a transmission or differential of a vehicle. 
     
     
       5. A propeller shaft in which the constant velocity universal joint according to any one of claims  1 - 4  is attached to the shaft portion thereof. 
     
     
       6. A propeller shaft comprising a shaft portion and a plurality of joints, 
       wherein at least one of the joints is a constant velocity universal joint comprising: an outer joint member in which eight guide grooves extending in the axial direction are formed on an inner spherical surface thereof; an inner joint member in which eight guide grooves extending in the axial direction are formed on an outer spherical surface thereof and an engagement portion having teeth which come into tooth-engagement with the shaft portion; eight torque transmitting balls disposed in eight ball tracks, respectively, each ball track formed by cooperation between one of the guide grooves in the outer joint member and a corresponding one of the guide grooves in the inner joint member; and a cage for holding the torque transmitting balls, wherein the ball tracks widened toward one side in the axial direction forming wedge shaped configurations, wherein  
       a ratio Rw (=W/PCD SERR ) between an axial width (W) in the axial direction of the inner joint member and a pitch circle diameter (PCD SERR ) of the teeth of the engagement portion is 0.57<Rw≦0.95 and a circumferential width (L) in the circumferential direction of the outer surface between the guide grooves of the inner joint member is L≦3.5 mm.